NRNP 6566 MIDTERM EXAM
WEEK 1 to 5
QUESTIONS AND CORRECT
VERIFIED ANSWERS
2025/2026
, NRNP 6566 Mid-term Exam Week 1 to 5
Week 1
1. Describe the cytochrome P450 system. Describe how inducers and inhibitors affect the
cytochrome system and how that affects the half-life of medications.
Cytochromes P450 (CYPs) are a superfamily of enzymes containing heme as a cofactor that
function as monooxygenases. In mammals, these proteins oxidize steroids, fatty acids, and
xenobiotics, and are important for the clearance of various compounds, as well as for hormone
synthesis and breakdown. Cytochrome P450 enzymes can be inhibited or induced by medicines,
resulting in clinically significant medicine-medicine interactions that can cause unanticipated
adverse reactions or therapeutic failures. Fluoxetine, sertraline, and fluvoxamine are believed to
inhibit cytochrome P450 2C because of observed interactions with phenytoin, diazepam, and
other medicines metabolized by these enzymes. Rifampicin and isoniazid are key medicines used
in the cure of tuberculosis, while rifampicin is highly effective in inducing hepatic, medicine
metabolicP450 enzyme.
The mnemonic SICKFACES.COM can be used to easily remember common cytochrome
P450 inhibitors.
1. Sodium valproate.
2. Isoniazid.
3. Cimetidine.
4. Ketoconazole.
5. Fluconazole.
6. Alcohol & Grapefruit juice.
7. Chloramphenicol.
8. Erythromycin.
2. Describe the affect on low and high albumin levels on active medicine levels
especially formedicines that are highly protein bound.
Downloaded by dennis murimi ()
, Albumin is the plasma protein with the greatest capacity for binding medicines. Binding to
plasma proteins affects medicine distribution into tissues, because only medicine that is not
bound is available to penetrate tissues, bind to receptors, and exert activity. As free medicine
leaves the bloodstream, morebound medicine is released from binding sites. Some medicines
have a high affinity for binding to serum proteins and may be 95% to 98% protein bound. With
highly protein bound medicines, low albumin levels (as in protein-calorie malnutrition, or
chronic illness) may lead to toxicity because there are fewer than the normal sites for the
Downloaded by dennis murimi ()
WEEK 1 to 5
QUESTIONS AND CORRECT
VERIFIED ANSWERS
2025/2026
, NRNP 6566 Mid-term Exam Week 1 to 5
Week 1
1. Describe the cytochrome P450 system. Describe how inducers and inhibitors affect the
cytochrome system and how that affects the half-life of medications.
Cytochromes P450 (CYPs) are a superfamily of enzymes containing heme as a cofactor that
function as monooxygenases. In mammals, these proteins oxidize steroids, fatty acids, and
xenobiotics, and are important for the clearance of various compounds, as well as for hormone
synthesis and breakdown. Cytochrome P450 enzymes can be inhibited or induced by medicines,
resulting in clinically significant medicine-medicine interactions that can cause unanticipated
adverse reactions or therapeutic failures. Fluoxetine, sertraline, and fluvoxamine are believed to
inhibit cytochrome P450 2C because of observed interactions with phenytoin, diazepam, and
other medicines metabolized by these enzymes. Rifampicin and isoniazid are key medicines used
in the cure of tuberculosis, while rifampicin is highly effective in inducing hepatic, medicine
metabolicP450 enzyme.
The mnemonic SICKFACES.COM can be used to easily remember common cytochrome
P450 inhibitors.
1. Sodium valproate.
2. Isoniazid.
3. Cimetidine.
4. Ketoconazole.
5. Fluconazole.
6. Alcohol & Grapefruit juice.
7. Chloramphenicol.
8. Erythromycin.
2. Describe the affect on low and high albumin levels on active medicine levels
especially formedicines that are highly protein bound.
Downloaded by dennis murimi ()
, Albumin is the plasma protein with the greatest capacity for binding medicines. Binding to
plasma proteins affects medicine distribution into tissues, because only medicine that is not
bound is available to penetrate tissues, bind to receptors, and exert activity. As free medicine
leaves the bloodstream, morebound medicine is released from binding sites. Some medicines
have a high affinity for binding to serum proteins and may be 95% to 98% protein bound. With
highly protein bound medicines, low albumin levels (as in protein-calorie malnutrition, or
chronic illness) may lead to toxicity because there are fewer than the normal sites for the
Downloaded by dennis murimi ()
